Electrically heated mattress



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Patented Aug. 12, 1952 ELECTRICALLY HEATED MATTRESS Oliver D. Westerbergand Wallace H. Englchardt, Chicago, lll., assignors to Tempret Products,lInc., a corporation of Illinois Application January 1s, 1949, seran No.71,542

(ci. 21e-46) 1l Claims.

'I'his invention is directed to an Yelectrically heated mattress and anelectric heating unit therefor.

An object of this invention is to provide an electrically heatedmattress Which enhances sleeping comfort during cold weather. Themattress or this invention preferably includes an innerspring unit, awire grid overlying the upper surface ci' the innerspring unit, a hardliber pad overlying the grid, a soft iiber pad overlying the hard iiberpad, an electrical heating unit overlying the soft iiber pad and laquilted covering including a soft fiber pad overlying the electricheating unit. In assembling the mattress, the Various elements thereofare secured together for the purpose of preventing undue` shiftingthereof with respect to each other. In this Way the electrical heatingunit is maintained in fixed position within the mattress.

By experiment and actual use itis found that better sleeping comfort isobtained vby the use of the electrically heated mattress of thisinvention than by conventional heated blankets or quilts now in use.Because the mass of the mattress of this invention, in which theelectrical heating unit is inserted, is greater than the mass of aconventional electrically heated blanket or quilt, more uniform andsteady temperatures can be maintained and widely iiuctuatingtemperatures are avoided. Since the electrical heating unit is imbeddedin the mattress which is usually covered With a suitable blanket orquilt when in use, the heat loss from the electrically heated mattressis considerably less than in the case of an electrically heated blanketor quilt and the electrical heating unit is less affected' by changes inambient temperatures.

Since the electrical heating unit is maintained in fixed relation in themattress, it cannot be folded or distorted as in the case oftheelectrical heating units of electrically heated blankets or quilts.Thus, the danger of short circuiting resulting in overheating, spotheating and occasionally re existing in electrically heated blankets orquiltscannot occur in the electrically heated mattress of thisinvention. Accordingly, there isv no need ,for safety thermostats, fusesand the like as are at present requiredin electrically heated blanketsorquilts. In fact, the electrically heated mattress of this invention' hasobtained approval of Underwriters Laboratories, Inc. even though itincludes no thermostatic switches, fuses, or the like.

Another object of this invention is to provide an electrical heatingunit for incorporation in a mattress for electrically heating the same.In this connection Vthe electrical heating,r unit preferably includes aIiexible sheet adapted to be secured at its margins to the mattress andan elongated electrically heated element laced `at regular intervalsthrough the iiexible sheet in regularly spaced reversing rows. Thespacing of the lacing and rows is such that when the iiexible sheet isheld substantially spread it is impossible for one portion of theelectrical heating element to contact another portion thereof wherebyshort circuiting is entirely eliminated. In lacing the electricalheating element in the exible sheet, the sheet is preferably fan foldedat regular intervals, the electrical heating element is reverselythreaded through the ian folds at regular intervals and then theiiexible sheet is extended to remove the fan folds. In this way theelectrical heating element may be quickly and inexpensively lacedthrough the flexible sheet.

In the mattress construction, the wire grid, the hard liber pad and thesoft fiber pad contained between the electrical heating unit and theinnerspring unit effectively prevents the electrical heating unit frombeing contacted by and short circuited by the springs of the innerspringunit. The quilted cover including the soft fiber pad overlying theelectrical heating unit eifectively prevents the electrical heating unitfrom being damaged from the surface of the matress. The soft fiber padson either side of the electrical heating unit operate in conjunctiontherewith to provide substantially uniform and steady temperatureconditions.

A further object of this invention is to provide an improved electricalconnection between the electrical heating elementof the electricalheating unit andan extension cord which extends outwardly from themattress whereby dislocation and damage to the electrical heatingelement by pulling upon the extension cord is entirely eliminated. Inthis respect a piece of relatively strong material is suitably securedto the flexible sheet forforming a pocket in which the electricalconnections are made. j

Furtherobjects of this invention reside in the details of constructionof the electrically heated mattress andthe electrical heating unittherefor and the cooperative relationship between the component partsthereof.

Other objects and advantages will become apparent to those skilled inthe art upon reference to the accompanying specification, claims anddrawings in which: Y

Figure 1 is a plan view of the electrically heated mattress of thisinvention in twin bed size;

Figure 2 isa plan view of the electrically heated mattress of thisinvention'in double. bed size;

Figure 3 is a perspective view of the electrically 3 heated mattress ofthis invention with portions thereof cut away for illustration purposes;

Figure 4 is a vertical sectional view through one form of theelectrically heated mattress of this invention;

Figure 5 is a plan View of the electrical heating element;

Figure 6 is a view illustrating the manner of lacing the electricalelement in the sheet of the electrical heating unit;

Figure 7 is a sectional view of another form of the electrically heatedmattress and Figure 8 is an enlarged plan view of a portion of theelectrical heating unit.

The electrically heated mattress of this invention is generallydesignated at I in a twin bed size and is generally designated at Il ina double bed size. The twin bed mattress IIl is approximately 74 incheslong, 38 inches wide and 61/2 inches thick and the double bed mattressII is approximately 74 inches long, 53 inches wide and 61/ inches thick.

The electrically heated mattress preferably includes an innerspring unitI2 made up of a plurality of coil springs I3 which are bound together bywire lacing I4. The marginal edges of the innerspring unit I2 areprovided with a border frame I5. In this respect the innerspring unit isof conventional construction.

Overlying the upper surface of the innerspring unit I2 is a wire gridformed of a plurality of spaced parallel wires I6 suitably maintained inspaced relation. Overlying the wire grid is a hard fiber pad I'I such asa sisal pad. The marginal edges of the pad are rolled over the borderframe l as at I8 and suitably secured as by staples I9. Overlying thehard ber pad I'I is a soft fiber pad 2l) such as a six pound cotton feltpad.

The electrical heating element overlies the soft fiber pad 20 and itincludes a flexible sheet 22 formed of cotton muslin. Preferably theflexible sheet is substantially 72 inches long and 36 inches wide andthe same sheet may be utilized for twin bed mattresses as Well as doublebed mattresses. The electrical heating element 23' is laced through theflexible sheet at regular intervals in regularly spaced reversing rows.The rows extend substantially to the foot margin and the side margins ofthe flexible sheet but are spaced from the head margin thereof. Inlacing the electrical heating element 23 through the flexible sheet 22,the flexible sheet is preferably fan folded at regular intervals at 24as illustrated in Figs. 5 and 6. The electrical heating element is thenreversely threaded through the fan folds at regularly spaced intervalsand then the flexible sheet is extended to remove the fan foldswhereupon the lacing appears as in Fig. 5.

The electrical heating element consists of a Fortizen core upon which iswrapped a cupron wire of BS gauge #35 at about 40 turns per inch.

The wound wire is coveredlvvith a vinyl chloride` plastic covering such.as VCR-55. The heating element thus formed has about three ohms perfoot resistance at .5 ampere. About 85 feet of the heating element islaced into the flexible sheet. The lacing of the heating element in theflexible sheet is regular at about 2 inches and the rows are regularlyspaced apart about 2 inches. The effective area of the heating elementis therefore about 52 inches x 34 inches. 'Ih-ere is substantially a 2inch margin at the sides and the foot of the heating element and an 18inch margin at the head of the element.

The two ends of the heating element 23 terminate in a pocket 25 formedof a heavy material such as canvas, yas illustrated in more detail inFig. 8. The pocket 25 is formed by folding the canvas and stitching thebottom thereof as at 26 to the flexible sheet 22. An extension cord 21enters the pocket 25 through a hole in the fold and the extension cordis preferably knotted within the pocket as at 28. The two wires of theextension cord are electrically connected respectively to the two endsof the heating element 23 by means of metallic pressure clamps 29 whichare in turn bound and insulated by plastic tape 30. The pocket is closedand the joints 30 are bound in the pocket by heavy mattress twine 3I andlikewise the knot 28 is bound in the pocket by heavy mattress twine 32.Thus, the heating element and the extension cord and the connectionstherebetween are securely bound within the pocket 25 which in turn issecurely held on to the flexible sheet 22. This provides for a strainrelief to prevent damage to the heating element and its connection tothe extension cord in the event that the extension cord should beyanked. The extension cord 2'I may be provided with a suitable switch 33and a wall plug 3'4.

Overlying the electrical heating unit is a quilted covering having asoft fiber pad 40, an undersheet 4I and a covering sheet 42. Preferablythe soft fiber pad is made from 6 pound cotton felt, the under sheetfrom muslin and the covering sheet from suitable ticking. The pad,undersheet and covering sheet are preferably quilted as at 43.

As shown in Figs. 3 and 4, the flexible sheet 22 of the electricalheating element may be secured at its margins to the undersheet 4I ofthe quilted pad `as by stitching 44. Since the electrical heating unitis thus marginally secured to the quilted cover it is held in extendedposition and danger of crossing and contacting of adjacent portions ofthe electrical heating element 23' is entirely eliminated. The stitching44 is somewhat loose to provide a limited degree of strain releasebetween the electrical heating unit and the quilted cover, but yet,maintains the electrical heating unit in extended condition.

The soft fiber pad 4D and the undersheet 4I of the quilted covermarginally extend beyond the innerspring unit and the marginal edgesv ofthe undersheet 4I are carried over the rolled edge I8 of the hard fiberpad I'I and secured thereto by staplesv 45. In this way the quiltedcover and the electrical heating element are firmly secured to theinnerspring unit. The soft ber pad 40 extends downwardly over the sideof the mattress for padding the side. A side panel 46 covers the sidesof the mattress and is secured to the cover sheet 42 of the quiltedcover in a suitable seam 41. As shown in Fig. 4 the extension cord 2'Imay extend outwardly from the mattress through the seam 41.

The form of the electrically heated mattress illustrated in Fig. 7 isessentially the same as that illustrated in Fig. 4 and'like referencecharacters for like parts have been utilized. It differs, however, inthe manner of securing the electrical heating element to the m'attressand the manner of bringing out the extension cord. In Fig..7 theflexible sheet '22 of the electrical heating element is made larger thanheretofore explained and instead of being stitched to the undersheet ofthe quilted cover, it is secured to the innerspring unit by staples 45.If desired, the staples 45 may also secure the undersheet 4I of thequilted cover to the nnerspring unit. Instead of extendingrvtheextension` cord 21 through the seam If it maybe extended outwardlyfrom the mattress through a suitable grommet 50- carriedby the sidepanel 46 of the mattress.`

"Theelectrical heating unit is located between the two soft fiber `pads20 and 40 and is therefore protected against damage from the exterior ofthe mattressor from the innerspring unit.v The wire grid and' the hardfiber j pad effectively prevent the soft fiber padl from working intothe coil springs of the innerspring unit and therefore adds to theprotection afforded the electrical heating unit. 'Since there isconsiderable mass on either side of the electrical heating unit, widelyfluctuating temperatures are Iavoided and uniform and steadytemperatures are maintained.

. While for purposes of illustration two forms of this invention havebeen disclosed, other forms thereofv may become apparent to thoseskilled in thecart upon reference to this disclosure,V and therefore,this invention is' to be limited only by the scope of the lappendedclaims.

We claim as' our invention:

1;y An electrical heating unit for incorporation ln a mattress" forelectrically heating the same comprising, a flexible sheet adapted to besecured at its margins to the mattress, an elongated electric'al heatingelement laced at regular intervals through the exiblesheet in regularlyspaced reversing rows, a fabric piece folded upon itself and secured tothe flexible sheet adjacent one corner thereof to provide a pocket, theends of the electrical heating element terminating in the pocket, a twowire extension cord extending into the pocket and the wires thereofknotted together Within the pocket, electrical connections in the pocketbetween the ends of the electrical heating element and the ends of thewires of the cord, and twine for binding the electrical connections andthe knotted cord to the fabric piece forming the pocket.

2. An electrical heating unit for incorporation in a mattress forelectrically heating the same comprising, a flexible sheet having sidemargins and head and foot margins and adapted to be secured at itsmargins to the mattress, an elongated electrical heating element lacedat regular intervals through the flexible sheet in regularly spacedreversing rows parallel to the side margins, the rows extendingsubstantially to the foot margin of the flexible sheet but spaced fromthe head margin thereof. a fabric piece folded upon itself and securedto the flexible sheet adjacent the head margin thereof to provide apocket, the ends of the electrical heating element terminating in thepocket, a two wire extension cord extending into the pocket and thewires thereof knotted together within the pocket, electrical connectionsin the pocket between the ends of the electrical heating element and theends of the wires of the cord, and twine for binding the electricalconnections and the knotted cord to the fabric piece forming the pocket.

3. An electrically heated mattress comprising, an innerspring unit, awire grid overlying the upper surface of the innerspring unit, a hardfiber pad overlying the grid, a soft fiber pad overlying the hard fiberpad, and electrical heating unit overlying the soft fiber pad andincluding a ilexible sheet and an elongated electrical heating elementlaced at regular intervals through the flexible sheet in regularlyspaced reversing rows, and a quilted cover including a soft ber padoverlying the electrical heating unit,

4. An electrically heated mattress comprising,

an innersp'ringunit having aborder frame, a w-ire grid-overlying theupper surface vof the innerspring unit,'a hard fiber pad overlying thegridandextending 'over and secured tothe border frame of the'innerspringunit, a soft'ber pad overlying the hard fiber pad, anl electricalheating'unit overlying the soft fiber padfand including a flexible sheetand an elongated heating element laced at regular intervals through theflexiblev sheet in regularly spaced reversing rows, a quilted coveroverlying the electrical heating unit and including a soft fiber pad andan undersheet which extends over and is secured to the border frameofthe'inner spring unit, the flexible sheet Vof'thev electricalheating'funit being marginally secured tothe under sheet of the quiltedcover;

M5; An electricallyv heated mattress comprising, an innerspri'ng 4unithaving a border frame, a wire grid-overlying the upper surface of theinnerspring'unit, a hard' ber pad overlying the grid and extending overand secured to the border frame vof the innerspring unit, a soft fiberpad overlying the hard fiber pad, an electrical heating unit overlyingthe softfiber pad andV includinga flexible sheet `and anelongatedheating element/laced at regular intervals-through Vthe flexible sheetin regularly spaced reversing rows, the flexible sheet of the electricalheating unit extending-overand securedtol the border frame of theinnerspring unit, a quilted cover overlying the electrical heatingunit,and including asoft ber pad and an undersheet which extends over and issecured to the border frame of the innerspring unit.

6. An electrically heated mattress comprising, an innerspring vunit, awire grid overlying the upper surface of the innerspring unit, a hardfiber pad overlying the grid, a soft fiber pad overlying the hard berpad, an electrical heating unit overlying the soft fiber pad andincluding a flexible sheet and an electrical heating element carriedthereby, and a quilted cover including a soft fiber pad overlying theelectrical heating unit.

7. An electrically heated mattress comprising, an innerspring unithaving a border frame, a wire grid overlying the upper surface of theinnerspring unit, a hard fiber pad overlying the grid and extending overand secured to the border frame of the innerspring unit, a soft fiberpad overlying the hard fiber pad, an electrical heating unit overlyingthe soft fiber pad and including a flexible sheet and an electricalheating element carried thereby, a quilted cover overlying theelectrical heating unit and including a soft fiber pad and an undersheet which extends over and is secured to the border frame of theinnerspring unit, the flexible sheet of the electrical heating unitbeing marginally secured to the under sheet of the quilted cover.

8. An electrically heated mattress comprising, an innerspring unithaving a border frame, a wire grid overlying the upper surface of theinnerspring unit, a hard fiber pad overlying the grid and extending overand secured to the border frame of the innerspring unit, a soft fiberpad overlying the hard fiber pad, an electrical heating unit overlyingthe soft fiber pad and including a flexible sheet and an electricalheating element carried thereby, the flexible sheet of the electricalheating unit extending over and secured to the border frame of theinnerspring unit, a quilted cover overlying the electrical heating unitand including a soft fiber pad and an under sheet which extends over andis secured to the border frame of the innerspring unit.

9. An electrically heated mattress comprising, an innerspring, unit, awire grid overlying the upper surface of the innerspring unit, a hardber padpverlying the grid, a soft ber pad overlying the hard ber pad, anelectrical heating unit joverlying the soft fiber pad and including ailexible sheet and an electrical heating element carried thereby, aquilted cover including a. soft liber pad overlying the electricalvheating unit, aborder panel secured to the quilted cover, and anextension cord extending into the mattress and electrically connected tothe electrical heating element. y Y

10. An electrically heated mattress comprising. an innerspring unit, aWire grid overlying the upper surface of the innerspring unit, ahardber. pad overlying the grid, a soft fiber pad overlying the hard berpad, an electrical heating unit overlying the soft fiber pad andincluding a ilexible sheet and an electrical heating element carriedthereby, a quilted cover including a soft ber pad overlying theelectrical heating unit,ja border panel secured to the quilted cover,.and an extension cord extending into the mattress at the juncture ofthe border panel and quilted cover and electrically connected to theelectrical heating element.

k11. An electrically heated mattress comprising, an 4inner-spring unit,a wire grid overlying the upper surface of the innerspring unit, a hard30 fiber pad voverlying the grid, a soft fiber pad overlying the hardber pad, an electrical heating unit overlying the soft fiber pad andincluding a flexible sheet and an electrical heating elementcarriedthereby, a quilted coverkincludin'gavsoft fiber pad overlying theelectrical heating unit, a border panel secured to the quiltedcover, andan extension cord extending into the mattress through the border paneland electrically connected to the electrical heating element.

` OLIVER D. WESTERBERG. i WALLACE H. ENGLEHARDT.

REFERENCES CITED The following references are of record in the le ofthis patent: g y

UNITED STATES PATENTS Number Name Date 1,835,212 Fowler Dec. 8, 19311,837,117 Dunbar Dec. 15, 1931 1,881,198 Kirk Oct. 4,1932 1,957,401Wiedenmann May 1,' 1934 2,012,631 Kindermann et al. Aug. 27, 19352,162,021 Kidwell g June 13, 1939 2,265,535 e Lubeck Dec', 9, 19412,317,189 Heiser et al. Apr. 20, 1943 2,376,902 Clark May 29, 19452,439,892 Huck 1 Apr. 20, 1948 2,569,138 Abbott V Sept. 25, 1951 lFOREIGN PATENTS Number g Country Date 201,348 Great Britain v gAug.`2,11923

